Material Composition For A Coating For Components Of Internal Combustion Engines

ABSTRACT

The invention relates to a material composition for a coating for components of internal combustion engines, selected from one of the three material compositions indicated in the following table: formula.CMnCrBSiFe1. variant0.1-5%0.1-3% 0-2%0.0-1%remainder2. variant0.1-5%0.1-3%1-13%0.1-10%remainder3. variant0.1-5%0.1-3%8-30%0.1-10%remainder

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is filed pursuant to 35 USC 371 and claims priority benefit to PCT application PCT/EP2019/081762 filed Nov. 19, 2019 which claims priority benefit to German patent application number 102018129167.1 filed Nov. 20, 2018, the entire contents of both applications are incorporated herein by reference.

TECHNICAL FIELD

The invention relates to a material composition for producing a coating for components of internal combustion engines, in particular for cylinder and/or piston surfaces, according to the features of the preamble of the independent claims.

This coating for components of internal combustion engines, in particular for cylinder and/or piston surfaces, is suitable, for example, as a corrosion and wear-resistant cylinder surface for low friction in internal combustion engines. This corrosion- and wear-resistant cylinder surface for low friction in internal combustion engines is in turn particularly suitable for use in diesel engines.

BACKGROUND

There is a need to reduce the transitional friction for achieving a low fuel consumption and the increase in wear resistance and corrosion resistance to exhaust gas recirculation and bad fuel condensates for diesel engines from Euro 6.

From the prior art it is known to apply a plasma coating with powder of different chromium, molybdenum and solids content to components for internal combustion engines. Such a plasma coating is applied, for example, to cylinders made of stainless steel.

DETAILED DESCRIPTION

It is therefore the object of the invention to provide an improved corrosion and wear-resistant cylinder surface for low friction in internal combustion engines.

The object is achieved according to the invention by each one of the three material compositions listed in the following table.

C Mn Cr B Si Fe 1. variant 0.8% C 0.1-5% 0.1-3%  0-2% 0.0-1% remainder (preferably) 2. variant 9% Cr 0.1-5% 0.1-3% 1-13% 0.1-10% remainder (preferably) 3. variant 18% Cr 0.1-5% 0.1-3% 8-30% 0.1-10% remainder (preferably)

The FIGURES in the second column of the table above represent preferred values of the component used of the respective composition (that means that for the 1. variants carbon can be selected from the range between 0.1% and 5% carbon, preferably 0.8% carbon. The same applies to the other two variants. The 1. variant can also optionally contain 0.1-10% B, the 2. and/or 3. variant can contain independently of one another 0.0-5%, preferably 0.0-1% Si.

Accordingly, in preferred embodiments, the material composition can have one of the following material compositions:

C Mn Cr B Si Fe 1. variant  0.8% 0.1-3% 0-2%  optionally 0.1-10% 0.0-1% remainder 2. variant 0.1-5% 0.1-3%  9% 0.1-10% optionally 0.1-5% remainder 3. variant 0.1-5% 0.1-3% 18% 0.1-10% optionally 0.1-5% remainder

The material composition according to the invention can be used as a coating on components of internal combustion engines, in this case in particular, diesel engines. Components of internal combustion engines are in particular cylinder running surfaces, pistons, or inlet and outlet channels in the cylinder head. The cylinder running surfaces can be honed (i.e. smooth) or roughened before the coating with the material composition according to the invention is applied.

The chromium content increases the wear resistance and corrosion resistance of the coating. The coating according to the invention leads to an improvement in the exhaust gas behavior and to a reduction in fuel consumption.

The material composition according to the invention is preferably supplied to the coating process in the form of wire. However, other designs are not excluded.

The coating is preferably applied to the components using the “Plasma Transferred Wire Arc” (PTWA) process, in particular in the form of a wire.

The material composition which is present as a wire, can be applied, for example, using a wire spraying process, for example PTWA with alloyed solid wires or with supplementary wire filled with solids and optional smooth honing, on a component of internal combustion engines (especially cylinder running surfaces).

For example, a PTWA internal coating system is suitable for coating cylinder running surfaces. A PTWA (Plasma TransferredWire) coating system is a unit for coating bores with a diameter of 65 to 350 mm. The spray additive is supplied in the form of a wire. The nozzle unit may consist of a thorium-doped tungsten cathode, an air-cooled pilot nozzle made of copper and an electrically conductive wire-shaped supplementary material, which is supplied perpendicularly to the pilot nozzle. The plasma gas, a mixture of hydrogen and argon, is supplied through bores present in the cathode holder that are tangential to the circumference. The position of the cylinder bores creates a gas stream that is twisted along the cathode and escapes through the nozzle at high speed. The process is started by a high voltage discharge, which ionizes and dissociates the plasma gas between the pilot nozzle and the cathode. The plasma generated in this way flows at high speed through the nozzle orifice and expands along the longitudinal axis of the nozzle. The plasma is transported to the supplementary wire material that is continuously supplied perpendicularly to the nozzle, thereby closing the electrical circuit. Melting and atomization of the wire are influenced in two ways. On the one hand, the wire is resistance-heated by high currents, for example 65 to 90 amps. The impact of the plasma on the preheated wire ensures its melting and its atomization.

Devices for thermal coating a surface are described, for example, in U.S. Pat. No. 6,372,298 B1, U.S. Pat. No. 6,706,993 B1 and WO2010/112567 A1. The devices mentioned there have in common: a wire supply device for supplying a wire that is melting off, the wire acting as an electrode; a source of plasma gas for generating a plasma gas flow; a nozzle body with a nozzle opening through which the plasma gas flow is directed onto one end of the wire as a plasma gas jet; and a second electrode arranged in the plasma gas stream before it enters the nozzle opening. U.S. Pat. No. 6,610,959 B2 and WO2012/95371 A1 also deal with such devices.

An arc is formed between the two electrodes through the nozzle opening. The plasma jet emerging from the nozzle opening strikes the end of the wire, and, together with the arc, effects the wire to melt off and the molten wire material to be transported in the direction of the surface to be coated. Secondary air nozzles are attached in a ring around the nozzle opening, which secondary air nozzles generate a secondary gas jet that hits the material melted off from the wire end and thus effects an acceleration of the transport in the direction of the surface to be coated and secondary atomization of the melted wire material.

Today's internal combustion engines or their engine blocks can be formed by casting a metal or light metal, such as aluminum, with aluminum blocks in particular having an iron or metal layer on their cylinder bores.

The coating according to the invention is particularly suitable for components that are formed by casting a metal or light metal. In particular, this can be components made of an aluminum alloy and that have a metal layer to which then the coating of the material composition according to the invention is applied. The components can be formed, for example, by casting an aluminum alloy having an iron layer onto which the coating is applied.

The metal layer can be thermally sprayed onto the component. In addition to two-wire arc spray processes (TWA), HVOF spray processes and plasma powder spray processes, the above-mentioned processes are known as plasma wire spray processes or also as PTWA (Plasma Transferred Wire Arc) as thermal spray processes. A coating of the cylinder bores using the plasma wire spray processes, i.e. with the PTWA, is advantageous because a coating can be produced that has a positive effect on a reduced wear factor, on a longer service life of the internal combustion engine with lower oil consumption compared to conventional liners with cast liners made of gray cast iron material. 

1. A material composition for a coating for components of internal combustion engines, selected from one of the two material compositions listed in the following table: C Mn Cr B Si Fe variant A 0.1-5% 0.1-3% 1-13% 0.1-10% remainder variant B 0.1-5% 0.1-3% 8-30% 0.1-10% remainder


2. The material composition according to claim 1, characterized by the material composition: C Mn Cr B Si Fe 0.1-5% 0.1-3% 0-9% 0.1-10% 0.1-5% remainder


3. The material composition according to claim 1, characterized by the material composition: C Mn Cr B Si Fe 0.1-5% 0.1-3% 18% 0.1-10% 0.1-5% remainder


4. (canceled)
 5. A method of coating at least one component present in an internal combustion engine, the method comprising the step of: applying a coating composition to at least one surface of the at least one component of an internal combustion engine, the coating composition selected from the group consisting of: a. a composition consisting essentially of between 0.1 to 5% carbon, between 0.1 and 3% manganese, between 1 to 13% chromium, between 0.1 and 10% boron and iron; b. a composition composition consisting essentially of between between 0.1 to 5% carbon, between 0.1 and 3% manganese, between 8 to 30% chromium, between 0.1 and 10% boron and iron; c. a composition composition consisting essentially of between between 0.1 to 5% carbon, between 0.1 and 3% manganese, between 0 and 2% chromium, between 0.1 and 10% boron, between 0 and 1% silicon and iron
 6. The method according to claim 5, characterized in that the coating composition application step include a “Plasma Transferred Wire Arc” (PTWA) process.
 7. The method according to claim 6, characterized in that the material composition is supplied to the “Plasma Transferred Arc Wire” (PTWA) process in the form of a wire.
 8. The method according to claim 5, characterized in that the components are formed by casting a metal or light metal.
 9. The method according to claim 5, characterized in that the at least one component of the internal combustion engine is formed by casting an aluminum alloy having a metal layer to which the coating is applied.
 10. The method according to claim 9, characterized in that the at least one component of the internal combustion engine is formed by casting an aluminum alloy having an iron layer to which the coating is applied.
 11. The method according to claim 9, characterized in that metal layer is thermally sprayed onto the component.
 12. The method according to claim 11, characterized in that the metal layer is thermally sprayed onto the component by means of a two-wire arc spray process (TWA), HVOF spray process, plasma powder spray process, plasma wire spray process or Plasma Transferred Wire Arc (PTWA) process.
 13. The method according to claim 6 characterized in that the coating is applied on the components by means of a “Plasma Transferred Wire Arc” (PTWA) process.
 14. The use according to claim 13, characterized in that the material composition is supplied to the “Plasma Transferred Arc Wire” (PTWA) process in the form of a wire.
 15. The method according to claim 14, characterized in that the at least one component of the internal combustion engine is formed by casting a metal or light metal.
 16. The method according to claim 15, characterized in that the at least one component of the internal combustion engine is formed by casting an aluminum alloy having a metal layer to which the coating is applied.
 17. The method according to claim 16 characterized in that metal layer is thermally sprayed onto the component.
 18. The method according to claim 11, characterized in that the metal layer is thermally sprayed onto the component by means of a two-wire arc spray process (TWA), HVOF spray process, plasma powder spray process, plasma wire spray process or Plasma Transferred Wire Arc (PTWA) process. 